1. Field of the Invention
The present invention relates to a motor sensing circuit, and more particularly to a motor sensing circuit with transient voltage suppression to suppress transient voltage inputted from a signal output terminal thereof.
2. Description of the Related Art
A conventional motor sensing circuit 9 of a motor driver circuit is shown in FIG. 1. The conventional motor sensing circuit 9 includes an electrical switch 90 and a signal output terminal 91 for outputting a sensing signal. Said signal output terminal 91 is preferably selected from a sensing port of the motor driver circuit, such as a FG (frequency generation) pin or a RD (rotation detection) pin of a motor driver IC of the motor driver circuit.
However, in order to avoid distortion of the sensing signal that is generally a signal of sine wave, a conventional way to bypass a high transient voltage that is caused by a lightening stroke or electrostatic discharge through a bypass capacitor is not usable. Thus, the motor driver circuit is vulnerable when an impulse inputs the motor driver circuit through the signal output terminal 91 of the motor sensing circuit 9. Accordingly, there is a need for redesigning the conventional motor sensing circuit.